Nothing ruins a cozy evening at home quite like a cold draft sneaking in around a window. You feel it when you walk past, you see your energy bills climbing, and you might even notice your curtains fluttering slightly on a windy day. The good news is that you don’t have to replace the whole window to stop that leaky feeling. With a few simple tools and a little patience, you can seal up most drafts yourself and keep your house warmer in winter and cooler in summer. Let’s walk through the most common causes of window drafts and the DIY fixes that actually work.

First, you need to figure out where the air is getting in. On a breezy day, hold a lit incense stick or a candle flame near the edges of your window frame. If the smoke or flame dances or gets blown sideways, you have found a leak. Check the gap between the sash and the frame, around the window stop, and along the sill. You might also feel a draft coming from the gap where the window meets the wall, especially if your home is older and the framing has settled. Once you know where the draft lives, you can choose the right fix.

The most common culprit is worn-out or missing weatherstripping. Over time, that felt strip or foam tape on the sides and top of your window gets compressed, falls off, or just stops doing its job. Replacing it is one of the easiest and cheapest upgrades you can make. You can buy adhesive-backed foam or rubber weatherstripping at any hardware store. Just measure the perimeter of your window sash and cut the material to length. Clean the surface where you will stick it, peel off the backing, and press it firmly into place. Make sure the window can still close and latch smoothly without squishing the strip too much. For windows that slide open, you might prefer V-shaped vinyl weatherstripping that fits into the track. It’s a little trickier to install, but it lasts longer.

Another place drafts hide is the gap between the window frame and the wall of your house. That space is usually filled with expanding foam or caulking, but over years of temperature changes and house movement, it can crack or shrink. If you feel a draft right where the wooden window frame meets the drywall or siding, grab a tube of exterior-grade caulk. A simple caulking gun will help you apply a smooth bead along the seam. For interior drafts, use a paintable caulk that matches your trim so it doesn’t look ugly. For exterior drafts, choose a silicone-based caulk that won’t crack in the sun. Run a bead, smooth it with your finger or a caulking tool, and let it dry. You’ll be shocked how much that alone reduces drafts.

If your window has a storm window or a removable double-pane insert, check the seals around those. Sometimes the rubber gasket that holds the glass gets brittle. You can’t always replace that gasket yourself, but you can add a temporary fix: use removable rope caulk to fill the gap around the insert. Rope caulk looks like a thick putty rope, and you just press it into any crack you see. It stays flexible, seals well, and pulls off without damaging paint. Perfect for winter and you can remove it in spring.

For really old single-pane windows, you might want to add a layer of interior plastic shrink film. This isn’t the prettiest solution, but it works like a charm. Kits come with double-sided tape and a large sheet of clear plastic. You stick the tape around the window frame, press the plastic onto it, and then use a hair dryer to shrink the plastic tight. It creates an invisible barrier that stops drafts completely. You can still open the window if you install the film on a removable frame, but most people just put it up for the cold months and take it down when the weather warms up.

Don’t forget about the window locks. If your window doesn’t close tightly because the lock is loose or misaligned, air will leak in through the gap between the sash and the frame. Tighten the screws on the lock or latch, and if the sash itself has shifted, you can often adjust it by loosening the screws on the hinges (for casement windows) or by shimming the track (for sliding windows). A simple quarter-inch shim can make a big difference.

One last trick for a stubborn draft around a window that just won’t seal: use a draft stopper on the sill. These are long fabric tubes filled with sand or foam that you lay along the bottom edge of the window. They block air that sneaks under the sash. You can buy them or make your own from an old sock or fabric tube. They are not a permanent fix, but they work great as a quick solution while you plan a bigger repair.

Remember, fixing a drafty window is about layering your defenses. Start with weatherstripping, follow up with caulk, and add plastic film or draft stoppers if needed. Each step adds a little more comfort and saves a little more money. Plus, you get the satisfaction of knowing you tackled the problem yourself. Grab your candle, find the leak, and get sealing.